The invention relates to 5-alkyl-2-arylaminophenylacetic acids and derivatives thereof as defined herein which are particularly potent and selective cyclooxygenase-2(COX-2) inhibitors, methods for preparation thereof, pharmaceutical compositions comprising said compounds, methods of selectively inhibiting COX-2 activity and of treating conditions in mammals which are responsive to COX-2 inhibition using said compounds or pharmaceutical compositions comprising said compounds of the invention.
Various substituted 2-arylaminophenylacetic acids and derivatives thereof have been disclosed e.g. in J. Med. Chem. 33, 2358 (1990), U.S. Pat. Nos. 3,558,690, 3,652,762, 4,173,577 and 4,548,952, and in PCT applications WO94/04484, WO 97/09977, WO 96/00716 and DE 3,445,011 as analgesic agents, non-steroidal antiinflammatory agents and cyclooxygenase inhibitors. As to 5-alkyl-2-arylaminophenylacetic acids, the only example known to be described in the literature is 5-methyl-2-(2,6-dimethylanilino)-phenylacetic acid and its sodium salt (U.S. Pat. No. 3,558,690) for which no biological data has been reported.
2-(2,6-Dichlorophenylamino)phenylacetoxyacetic acid (aceclofenac) and salts thereof have been disclosed e.g. in U.S. Pat. No. 4,548,952, and in PCT application WO 96/00716 as non-steroidal antiinflammatory and analgesic agents. The pharmacological properties of aceclofenac are apparently the result of in vivo conversion to diclofenac and/or derivatives thereof.
Non-steroidal antiinflammatory agents block prostaglandin synthesis by inhibition of the enzyme cyclooxygenase. Cyclooxygenase is now known to comprise a constitutive isoform (cyclooxygenase-1, COX-1) and an inducible isoform (cyclooxygenase-2, COX-2). COX-1 appears responsible for protective beneficial features of prostaglandins, e.g. for the gastrointestinal tract, kidney, etc., while the inducible isoform COX-2 appears responsible for pathological conditions associated with prostaglandins, such as inflammatory conditions. A limitation to the use of conventional nonsteroidal antiinflammatory drugs (NSAIDS), including aceclofenac and diclofenac sodium which is the sodium salt of 2,6-dichloroanilinophenylacetic acid, is gastrointestinal toxicity now attributed to the inhibition of the COX-1 isoform of cyclooxygenase. Selective inhibition of inducible COX-2 in vivo has been reported to be antiinflammatory and non-ulcerogenic (Proc. Natl. Acad. Sci. (USA) 1994; 91:3228-3232).
The present invention provides novel 5-alkyl substituted 2-arylaminophenylacetic acids and derivatives which surprisingly inhibit COX-2 without significantly inhibiting COX-1. The invention thus provides novel nonsteroidal antiinflammatory agents which are surprisingly free of undesirable side effects usually associated with the classical nonsteroidal antiinflammatory agents, such as gastrointestinal and renal side effects. The compounds of the present invention are thus particularly useful or may be metabolically converted to compounds which are particularly useful as COX-2 selective cyclooxygenase inhibitors. They are thus particularly useful for the treatment of cyclooxygenase-2 dependent disorders in mammals, including inflammation, pyresis, pain, osteoarthritis, rheumatoid arthritis, migraine headache, cancer such as digestive tract (e.g. colon) cancer and melanoma, neurodegenerative diseases (such as multiple sclerosis), Alzheimer's disease, osteoporosis, asthma, lupus and psoriasis while substantially eliminating undesirable gastrointestinal ulceration associated with conventional cyclooxygenase inhibitors. The compounds of the invention are also UV absorbers, in particular UV-B absorbers, and are useful for blocking or absorbing UV radiation, for instance for the treatment and prevention of sunburn, e.g. in suntan products.
Ocular applications of the compounds of the invention include the treatment of ocular inflammation, of ocular pain including pain associated with ocular surgery such as PRK or cataract surgery, of ocular allergy, of photophobia of various etiology, of elevated intraocular pressure (in glaucoma) by inhibiting the production of trabecular meshwork inducible glucocorticoid response (TIGR) protein and of dry eye disease.
The compounds of the present invention are useful for the treatment of neoplasia particularly neoplasia that produce prostaglandins or express cyclooxygenase, including both benign and cancerous tumors, growths and polyps, in particular epithelium cell-derived neoplasia. Compounds of the present invention are in particular useful for the treatment of liver, bladder, pancreatic, ovarian, prostate, cervical, lung and breast cancer and, especially gastrointestinal cancer, for example cancer of the colon, and skin cancer, for example squamous cell or basal cell cancers and melanoma, as indicated above.
The term "treatment" as used herein is to be understood as including both therapeutic and prophylactic modes of therapy, e.g. in relation to the treatment of neoplasia, therapy to prevent the onset of clinically or preclinically evident neoplasia, or for the prevention of initiation of malignant cells or to arrest or reverse the progression of premalignant to malignant cells, as well as the prevention or inhibition of neoplasia growth or metastasis. In this context, the present invention is, in particular, to be understood as embracing the use of compounds of the present invention to inhibit or prevent development of skin cancer, e.g. squamous or basal cell carcinoma consequential to UV light exposure, e.g. resulting from chronic exposure to the sun.